New multidentate ligands for supramolecular coordination chemistry: Double and triple helical complexes of ligands containing pyridyl and thiazolyl donor units

Article abstract of DOI:10.1039/b007922g

Four new multidentate N-donor ligands L¹-L⁴ have been prepared which contain a combination of pyridyl and thiazolyl donor units. The syntheses of these ligands are facile and high-yielding, being based on reaction of an α-bromoacetyl unit with a thioamide to form the thiazolyl ring. The extended linear sequence of ortho-linked N-donor heterocycles (four for L¹, six for L²; five for L³; and six for L⁴) is reminiscent of the well-known linear oligopyridines, although these new ligands are much easier to make and have significantly different geometric coordination properties because the presence of the five-membered thiazolyl rings results in natural breaks of the ligand backbone into distinct bidentate or terdentate domains. Thus, the tetradentate ligand L¹ partitions into two bidentate domains to give dinuclear triple helicates [M₂(L¹)₃]⁴⁺ with six-coordinate first-row transition metal dications (M = Co, Cu, Zn). The hexadentate ligand L² partitions into two terdentate domains to give dinuclear double helicates [M₂(L²)₂]⁴⁺ with six-coordinate metal ions (M = Cu, Zn). In the double helicate [Cu₂(L³)₂]⁴⁺ the pentadentate ligand L³ only uses its two terminal bidentate binding sites, resulting in four-coordinate Cu(II) centres and a non-coordinated pyridyl residue in the centre of each of the two ligand strands. These pendant pyridyl residues are directed towards each other to give a potentially two-coordinate cavity between the metal ions in the centre of the helicate. Similarly, in the double helicate [Cu₂(L⁴)₂]⁴⁺ the metal ions are only four-coordinate, with each ligand having its central bipyridyl unit un-coordinated. This results in a potentially four-coordinate cavity between the two metal ions in the centre of the helicate. These easy-to-prepare ligands offer a great deal of scope for the development of multinuclear helicates.

Full text of DOI:10.1039/b007922g

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New multidentate ligands for supramolecular coordination
chemistry: double and triple helical complexes of ligands
containing pyridyl and thiazolyl donor units
a
b
b
b
b
Craig R. Rice,* Stefan Wörl, John C. Jeffery, Rowena L. Paul and Michael D. Ward†
a
Department of Chemical and Biological Sciences, University of Huddersfield, Huddersfield,
UK HD1 3DH. E-mail: c.r.rice@hud.ac.uk
School of Chemistry, University of Bristol, Cantock’s Close, Bristol, UK BS8 1TS
b
Received 2nd October 2000, Accepted 11th January 2001
First published as an Advance Article on the web 15th February 2001
1
4
Four new multidentate N-donor ligands L –L have been prepared which contain a combination of pyridyl and
thiazolyl donor units. The syntheses of these ligands are facile and high-yielding, being based on reaction of an
α-bromoacetyl unit with a thioamide to form the thiazolyl ring. The extended linear sequence of ortho-linked
1
2
3
4
N-donor heterocycles (four for L , six for L ; five for L ; and six for L ) is reminiscent of the well-known linear
oligopyridines, although these new ligands are much easier to make and have significantly different geometric
coordination properties because the presence of the five-membered thiazolyl rings results in natural breaks of the
1
ligand backbone into distinct bidentate or terdentate domains. Thus, the tetradentate ligand L partitions into two
1
4+
bidentate domains to give dinuclear triple helicates [M (L ) ] with six-coordinate first-row transition metal dications
(
2
3
2
M = Co, Cu, Zn). The hexadentate ligand L partitions into two terdentate domains to give dinuclear double
2
4
+
3
4
+
helicates [M (L ) ] with six-coordinate metal ions (M = Cu, Zn). In the double helicate [Cu (L ) ] the pentadentate
2
2
2
2
3
ligand L only uses its two terminal bidentate binding sites, resulting in four-coordinate Cu() centres and a
non-coordinated pyridyl residue in the centre of each of the two ligand strands. These pendant pyridyl residues are
directed towards each other to give a potentially two-coordinate cavity between the metal ions in the centre of the
4
4+
helicate. Similarly, in the double helicate [Cu (L ) ] the metal ions are only four-coordinate, with each ligand having
2
2
its central bipyridyl unit un-coordinated. This results in a potentially four-coordinate cavity between the two metal
ions in the centre of the helicate. These easy-to-prepare ligands offer a great deal of scope for the development of
multinuclear helicates.
9
Introduction
pseudo-tetrahedral geometry. Similarly, the hexadentate ligand
2
,2Ј : 6Ј,2Ј : 6Ј,2ٞ : 6ٞ,2ЉЉ : 6ЉЉ,2Ј-sexipyridine (spy) can be
Studies on the assembly of double and triple helicate complexes
have been a major area of activity in coordination chemistry for
the last 15 years or so. These assemblies have elegantly demon-
strated how the formation of architecturally complex systems is
directed by the interplay between simple parameters such as the
stereoelectronic preference of the metals ion and the disposition
partitioned into two terdentate or three bidentate binding
domains according to whether the metal ion prefers octahedral
10
[Cd()] or tetrahedral coordination [Cu()].
We describe in this paper the synthesis and coordination
chemistry of a series of polydentate N-donor ligands based on
pyridyl and thiazolyl donors. These may be considered as
analogues of the well-known polypyridines, but with two
important exceptions. Firstly, the incorporation of five-
membered thiazole units into the chain results in a natural
partition of the ligand into separate binding domains. The
coordination behaviour of these ligands can therefore be
controlled according to the position of the thiazole units in the
chain. Secondly, these ligands are exceptionally easy to prepare
in high yields using a simple modular approach; syntheses of
these ligands and their intermediates does not require chrom-
atographic purification at any stage. This paper reports the
syntheses of four new ligands and the structures of several
of their double- or triple-helical complexes with first-row
transition-metal ions. A preliminary communication describing
1
of the binding sites in the ligand.
A key parameter in the assembly of helicates is how a flexible
polydentate ligand becomes partitioned into distinct metal
binding sites. In many cases ligands have been constructed
which contain several bidentate or terdentate domains which
are so arranged that each site must necessarily bind a separate
metal ion rather than chelating to a single metal ion — a neces-
sary prerequisite for helication. Ligands of this type are
2
exemplified by the recent work of Albrecht et al., Piguet and
3
4
5
co-workers and Lehn and co-workers amongst others. In
other cases however, most notably the linear polypyridines
which have played a major role in the development of heli-
6,7
cates, the way in which the ligand is partitioned into binding
sites depends on the stereoelectronic preferences of the metal
ion which become all-important in directing the course of the
assembly. Thus, 2,2Ј : 6Ј,2Ј : 6Ј,2ٞ-quaterpyridine (qpy) acts as
a planar tetradentate chelate to first-row transition-metal
dications, as well as to Pd() and Pt(); but it acts as a 2 + 2
bridging ligand (two independent bipyridyl units) to Ag() and
Cu() in the dinuclear double helicates [M (qpy) ] whose
11
some of these results has appeared recently. We note that
thiazole units have also been incorporated into other poly-
dentate ligands by Connor and co-workers, who previously
4
prepared one of the ligands described in this paper (L ) but did
8,9
12
not describe any of its coordination chemistry.
2+
2
2
Results and discussion
assembly is driven by the preference of the metal ions for
Ligand syntheses
†
2
Royal Society of Chemistry Sir Edward Frankland fellow for 2000/
001.
The ligands described are shown in Scheme 1. The key step in
5
50
J. Chem. Soc., Dalton Trans., 2001, 550–559
This journal is © The Royal Society of Chemistry 2001
DOI: 10.1039/b007922g

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Scheme 1 Reagents and conditions: i, (COCH Br) , MeOH; ii, NH (aq); iii, 2-(α-bromoacetyl)pyridine, MeOH.
2
2
3
every synthesis is assembly of the thiazole unit from reaction of
an α-bromoacetyl group with a thioamide. The α-bromoacetyl
13
group is simply prepared by bromination of an acetyl group,
and the thioamide is equally simply prepared by reaction of a
12,14
cyano group with H S.
Using this methodology allows,
2
in principle, the preparation of a very wide variety of related
ligands, as long as components bearing acetyl or cyano sub-
stituents are available as starting materials.
1
Thus, L was prepared by reaction of two equivalents of
pyridine-2-thioamide with 1,4-dibromobutane-2,3-dione in
1
methanol at reflux. After 1 hour L precipitates cleanly as its
1
hydrobromide salt, from which free L is obtained quanti-
tatively by deprotonation with ammonia. Following the
2
same method, L was prepared from reaction of 1,10-phenan-
throline-2-thioamide with 1,4-dibromobutane-2,3-dione. Penta-
3
dentate L was prepared from pyridine-2,6-di(thioamide) with
2
-(α-bromoacetyl)pyridine, and the potentially hexadentate
1
4
3
Fig. 1 Crystal structure of
L
emphasising the intermolecular
ligand L was prepared in the same way as L but using 2,2Ј-
bipyridine-6,6Ј-di(thioamide). In all cases the ligands were
isolated in high yield as crystalline solids which were sufficiently
pure to be used for formation of metal complexes without
further purification, although samples for analysis were
recrystallised. All of the ligands gave correct elemental analyses
and showed the expected molecular ion in their EI mass
spectra. L , L (as the hydrobromide salt), L and L were
further characterised by H NMR spectroscopy (see the
Experimental section).
interactions. Bond lengths and angles within the molecule are
unremarkable.
adjacent stacks there are non-bonded S ؒ ؒ ؒ S interactions
S(1) ؒ ؒ ؒ S(1Ј), 3.475 Å; S(1) ؒ ؒ ؒ S(2Ј), 3.605 Å] and S ؒ ؒ ؒ N
interactions [N(1) ؒ ؒ ؒ S(2Ј), 3.276 Å] involving thiazole S and
pyridyl N atoms (Fig. 1). Such interactions are well known and
arise from interaction of the lone pair of the donor unit (N or
[
1
2
3
4
1
16
S) with a C–S(σ*) orbital from the acceptor unit (always S);
clearly these interactions exert a strong influence on the crystal
1
The crystal structure of L (Fig. 1) shows the molecule to be
packing in this case.
essentially planar, with an all-transoid geometry between the N
atoms of adjacent heterocyclic rings. In this respect the
structure is similar to those of the linear polypyridine ligands.
1
Dinuclear triple helicates with L
15
1
The molecules are arranged in canted stacks in the crystal with
separations between adjacent molecules (defined as the distance
from an atom in one molecule to the mean plane of the
next molecule) lying between 3.3 and 3.6 Å, which is normal
for aromatic π-stacking interactions. In addition, between
Although L is poorly soluble in common organic solvents, it
dissolves quickly on coordination to a metal ion to give soluble
complexes. Reaction of L with Co(ClO ) or Zn(ClO ) (in
nitromethane) or Cu(PF ) (in acetone) in a 3 : 2 ratio rapidly
1
4
2
4 2
6
2
afforded clear solutions of complexes, from which a good yield
J. Chem. Soc., Dalton Trans., 2001, 550–559 551

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Table 2 Selected bond distances (Å) and angles (Њ) for complexes
1
1
1
[
Cu (L ) ][PF ] ؒ4Me CO, [Co (L ) ][ClO ] ؒ4MeNO and [Zn (L ) ]-
2
3
6
4
2
2
3
4
4
2
2
3
[
ClO ] ؒ4MeNO
4
4
2
M = Co
M = Cu
M = Zn
M–N(21)
M–N(31)
M–N(61A)
M–N(11)
M–N(41)
M–N(51A)
2.130(5)
2.150(5)
2.182(6)
2.161(5)
2.138(6)
2.143(5)
2.028(8)
2.056(7)
2.171(8)
2.187(8)
2.192(8)
2.219(8)
2.150(4)
2.198(4)
2.194(4)
2.195(4)
2.164(5)
2.168(4)
N(21)–M–N(31)
N(21)–M–N(61A)
N(31)–M–N(61A)
N(21)–M–N(11)
N(31)–M–N(11)
N(61A)–M–N(11)
N(21)–M–N(41)
N(31)–M–N(41)
N(61A)–M–N(41)
N(11)–M–N(41)
N(21)–M–N(51A)
N(31)–M–N(51A)
N(61A)–M–N(51A)
N(11)–M–N(51A)
N(41)–M–N(51A)
172.7(2)
98.4(2)
83.6(2)
77.7(2)
100.6(2)
175.1(2)
95.4(2)
77.3(2)
98.5(3)
85.0(2)
86.9(2)
171.5(3)
96.7(3)
87.2(3)
79.2(3)
97.1(3)
175.4(3)
92.9(3)
79.1(3)
97.8(3)
84.8(3)
86.8(3)
101.4(3)
76.8(3)
100.5(3)
174.5(3)
171.94(16)
98.60(18)
84.46(16)
78.05(17)
99.40(15)
174.74(15)
95.07(17)
77.08(15)
98.22(19)
86.18(17)
88.58(16)
99.39(14)
76.81(15)
98.94(14)
174.25(15)
100.40(18)
76.9(2)
99.74(18)
175.1(2)
of crystalline product could be isolated in each case by dif-
fusion of ethyl acetate vapour into the solution. In each case,
electrospray mass spectroscopy and elemental analyses indi-
1
1
cated formation of a complex of the form [M (L ) ]X . The H
2
3
4
1
NMR spectrum of [Zn (L ) ][ClO ] in CD NO showed the
2
3
4 4
3
2
presence of just five resonances in the aromatic region of the
spectrum [Fig. 2(a)] (of which two are overlapping), indicating
that all six pyridyl–thiazolyl units are equivalent in solution
on the NMR timescale, which is only consistent with all three
ligands adopting a symmetrically bridging coordination mode.
This was confirmed by determination of the crystal structures
of all three complexes (see Tables 1 and 2).
All three complexes are dinuclear triple helicates and the
structures are very similar to one another (Figs. 3 and 4). In
each complex, both metal centres have a pseudo-octahedral
coordination geometry arising from coordination of three
thiazolyl–pyridyl bidentate units. To accommodate this bridg-
1
ing coordination mode, each ligand L is twisted about the
bond between the two thiazole rings (torsion angles in the range
5
8Њ to 79Њ) such that each ligand can present a bidentate binding
site to each metal ion without steric problems. The triple helical
structure is stabilised by extensive aromatic π-stacking inter-
actions between overlapping, near-parallel fragments of
adjacent ligands, as emphasised in the space-filling picture
(
Fig. 4). Details of the relevant structural parameters for each
complex are summarised in Table 2, with parameters that are
equivalent between structures positioned in the same row of the
table to facilitate comparison.
The only significant difference between the structures is in the
degree of distortion in the metal coordination spheres. Whereas
the Co() and Zn() complexes have a relatively narrow range
of M–N separations [2.13–2.18 Å for Co(); 2.15–2.20 Å for
Zn()], for the Cu() complex the bond distances lie between
2
.03–2.22 Å, a spread of ca. 10%. This is undoubtedly due to
the Jahn–Teller effect: although there is no single obvious axis
of elongation as usually occurs in complexes of tetragonal
symmetry, the distortion manifests itself in one axis [N(21)–
Cu–(31) axis, average Cu–N distance 2.04 Å] being significantly
shorter than the other two [N(11)–Cu–N(61A), average Cu–N
distance 2.18 Å; and N(41)–Cu–N(51A), average Cu–N dis-
tance 2.21 Å]. This apparent axial compression has been
ascribed to a dynamic Jahn–Teller effect in which a single axis
of elongation — the electronically most likely distortion —
17
is disordered over two axes. In this case it is clear from the
5
52
J. Chem. Soc., Dalton Trans., 2001, 550–559

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Fig. 4 Space-filling picture of the triple helical complex cation of
1
[
Zn (L ) ][PF ] .
2 3 6 4
1
The formation of triple helicates with L is in interesting
contrast to the many mononuclear complexes in which qpy acts
8
as a simple equatorial tetradentate chelate to a +2 metal ion. In
qpy this coordination mode is facilitated by the fact that all
three chelate rings have a bite angle appropriate for coord-
1
ination to a single metal ion. In L this is not the case; the two
five-membered thiazolyl rings cannot chelate well because the
N atoms of the two five-membered rings are not sufficiently
convergent, so the ligand naturally partitions into two bidentate
pyridyl–thiazolyl units with a twist in the ligand backbone
between them. The result is a dinuclear triple helicate instead of
a simple mononuclear complex.
2
Dinuclear double helicates with L
1
1
Fig. 2 H NMR spectra of (a) the triple helicate [Zn (L ) ][ClO ] , and
1
2
3
4
4
Given the way that L was observed to behave, we might expect
2
(
b) the double helicate [Zn (L ) ][ClO ] (MeNO , 300 MHz).
2
2
2
4
4
2
that L partitions into two terdentate domains with the break
occurring between the two thiazolyl rings. Reaction of L with
2
Cu(ClO4)2 or Zn(ClO4)2 afforded complexes for which the
elemental analyses were consistent with the empirical formul-
2
ation [M(L )](ClO ) ; electrospray mass spectra indicated the
4
2
2
4+
formation of dimeric complex cations [M (L ) ] (M = Cu,
2
2
1
Zn). The H NMR spectrum of the Zn() complex [Fig. 2(b)]
shows the presence of eight aromatic proton environments,
indicating a high-symmetry structure in which all four ligand
halves are chemically equivalent.
The crystal structures of both complexes reveal that they
are dinuclear double helicates, with each metal ion being
six-coordinate from two terdentate fragments, one from each of
the two ligands (Figs. 5 and 6). The bridging coordination mode
of each ligand is facilitated by a twist of ca. 90Њ between the two
2
4+
thiazolyl rings. In [Cu (L ) ] (Fig. 5) the two metal centres are
2
2
in a very irregular coordination environment, but it is non-
etheless clear that one of the axes is substantially shorter than
the other two at each metal centre. For Cu(1), the N(144)–
Cu(1)–N(121) axis (average Cu–N distance, 1.98 Å) is shorter
than the N(101)–Cu(1)–N(141) and N(111)–Cu(1)–N(124) axes
(
average Cu–N distances, 2.23 and 2.17 Å respectively). For
Cu(2), the N(244)–Cu(2)–N(221) axis (average Cu–N distance,
.97 Å) is shorter than the N(201)–Cu(1)–N(241) and N(211)–
1
Cu(1)–N(224) axes (average Cu–N distances, 2.22 and 2.23 Å
respectively). As with any Cu() complex in a constrained
geometry it is not easy to know to what extent this distortion is
due to the Jahn–Teller effect, and to what extent it is imposed
by the ligand set, however comparison with the Zn() complex
provides some clues. In fact, the crystal structure of the Zn()
1
Fig. 3 Crystal structure of the complex cation of [Cu (L ) ][ClO ]
4 4
2
3
[
the structures of the Co() and Zn() analogues are essentially
identical apart from minor changes in bond lengths/angles in the metal
coordination sphere].
2
4+
double helicate [Zn (L ) ] also shows a similar pattern with
2
2
one axis having shorter bond lengths than the other two. For
Zn(1), the N(141)–Zn(1)–N(124) axis has a mean Zn–N dis-
tance of 2.07 Å; for the axes N(111)–Zn(1)–N(121) and
N(101)–Zn(1)–N(144) the mean Zn–N distances are 2.20 and
2.21 Å respectively. Around Zn(2), the short axis is N(221)–
Zn(2)–N(244), with a mean Zn–N distance of 2.05 Å; for the
comparison between the distorted Cu() complex, and the
more regular Co() and Zn() complexes, that the structural
1
4+
distortion of [Cu (L ) ] arises from a genuine stereoelectronic
2
3
preference of the metal ion, rather than being imposed by the
ligand.
J. Chem. Soc., Dalton Trans., 2001, 550–559
553

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3
Fig. 7 Crystal structure of the complex cation of [Cu (L ) ][ClO ] .
2
2
4 4
2
Fig. 5 Crystal structure of the complex cation of [Cu (L ) ][ClO ]
4 4
2
2
[
the structure of the Zn() analogue is essentially identical apart from
minor changes in bond lengths/angles in the metal coordination
sphere].
3
4+
Fig. 8 Alternative view of the complex cation [Cu (L ) ] ,
2
2
emphasising the two-coordinate cavity at the centre of the helicate.
Fig. 6 Space-filling picture of the double helical complex cation of
3
4
2
Dinuclear double helicates with L and L showing hypodentate
coordination
[
Zn (L ) ][ClO ] .
2
2
4 4
3
axes N(211)–Zn(2)–N(241) and N(201)–Zn(2)–N(224) the
mean Zn–N distances are 2.23 and 2.19 Å respectively. These
differences are sufficiently large to be significant even consider-
ing the poor quality of the structure of the Zn complex.
The potentially pentadentate ligand L contains thiazolyl units
at positions 2 and 4 of the five-ring sequence. Whilst a bidentate
pyridyl–thiazolyl fragment can clearly act as an effective biden-
tate chelate (cf. complexes with L ), simple molecular modelling
suggests that a terdentate pyridyl–thiazolyl–pyridyl unit — with
the five-membered thiazolyl ring in the centre — cannot easily
act as a terdentate chelate as the two terminal pyridyl units are
not sufficiently convergent. The way in which L could be
partitioned into separate binding domains is therefore not as
clear as it is for L and L : there are several ways in which two
bidentate pyridyl–thiazolyl fragments can be donated to metal
ions, but these will all result in a spare pyridyl donor (hypo-
1
2
4+
The pattern of metal–ligand bond lengths in [Zn (L ) ]
2
2
2
4+
therefore matches well that seen for [Cu (L ) ] , although the
2
2
difference in length between the one short and the two long axes
is more pronounced for the Cu() complex. This suggests that
the coordination geometry is largely imposed by the ligand set,
and is less easily ascribed to stereoelectronic effects — in direct
3
1
2
1
contrast to the behaviour of the triple helicates with L (see
above). In every case the short axis is the one with two bonds to
the central donor atom of each terdentate unit. We are therefore
seeing a structural distortion of the type typical of terpyridyl
complexes, where the M–N distance to the central pyridyl ring
is significantly shorter than the bonds to the two terminal pyr-
6
dentate coordination of the ligand).
This behaviour is illustrated by the crystal structure of
[Cu (L ) ][ClO ] , (Figs. 7 and 8) which was prepared by reaction
of Cu(ClO ) with L , in the same manner as for the earlier
complexes. The complex cation is again a double helicate, with
two four-coordinate Cu ions each coordinated by two bidentate
pyridyl–thiazolyl units, one from the terminus of each ligand.
The result of this is that the central pyridyl residue of each
ligand is not coordinated, but just acts as an innocent spacer
3
2
2
4 4
3
4
2
18
idyl rings. This is a consequence of the fact that the natural
bite angle of terpyridine, which is 120Њ, is mis-matched with the
usual preference of the metal centre for a bite angle of 180Њ
from a terdentate chelate, and similar geometric behaviour is
2
shown by the thiazolyl–phenanthroline unit of L .
5
54
J. Chem. Soc., Dalton Trans., 2001, 550–559

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group separating the two bidentate binding sites. Across the
centre of the complex, the non-bonded N ؒ ؒ ؒ N separation
between the two non-coordinated pyridyl residues is 4.36 Å.
The geometry about the two Cu() ions is of the type generally
described as pseudo-tetrahedral, although the two bidentate
fragments at each metal centre are not mutually perpendicular.
At Cu(1) the dihedral angle θ between the two Cu(NN) planes
is 47.5Њ, so the geometry is almost mid-way between planar (D2h
local symmetry of the CuN unit, arising from θ = 0Њ between
4
the two CuNN planes) and tetrahedral (D2d local symmetry of
the CuN unit, arising from θ = 90Њ between the two CuNN
4
planes). At Cu(2) this dihedral angle θ is 49.7Њ. In addition,
there is extensive aromatic π-stacking between overlapping,
near-parallel segments of the two ligands with average inter-
planar distances in the region of 3.5–3.7 Å. The Cu ؒ ؒ ؒ Cu
separation is 4.325 Å.
It is interesting to note that the irregular four-coordinate
geometry, and the range of Cu–N bond distances (1.97–2.07
Å), are also typical of Cu() centres with NN-chelating ligands
19
such as derivatives of bipyridine and phenanthroline. From
the crystal structure alone it is not obvious whether the oxid-
ation state of the metal is +2 or +1, although we note that for
I
19
Cu (NN) complexes the value of θ is usually 70–80Њ, com-
2
pared to 45–50Њ in this helicate which is more suggestive of
Cu(). Although there are four counter-ions, it is in principle
possible that the pendant pyridyl units could be protonated
such that the four positive charges are provided by two Cu()
centres and two protons. The ambiguity is simply resolved by
4
Fig. 9 Crystal structure of the complex cation of [Cu (L ) ][ClO ] .
2
2
4 4
the electronic spectrum of the complex in MeNO , which
2
Ϫ1
Ϫ1
reveals a transition at λmax = 706 nm (ε ca. 300 M cm ) with
a low-energy shoulder at around 900 nm. This is entirely char-
acteristic of Cu() in an irregular coordination environment,
for which up to four d–d transitions may be expected, although
usually only one or two are resolved due to their width and the
20
close spacing of the individual maxima. In addition, an EPR
spectrum of the complex in MeNO solution confirmed that is
2
paramagnetic with a broad transition centred at g = 2.14; in a
frozen solution at 77 K the spectrum remained broad and
poorly resolved with only a single feature present at g = 2.12.
These spectra are indicative of weak Cu–Cu magnetic exchange
which broadens the signal to an extent which precludes any
geometric analysis of the results, but the presence of a strong
signal in this position confirms the oxidation state assigment as
Cu().
4
The crystal structure of [Cu (L ) ][ClO ] (Figs. 9 and 10)
2
2
4 4
shows similar hypodentate behaviour with only the terminal
bidentate pyridyl–thiazolyl units coordinated to the metal ions
and consequently a central non-coordinated bipyridyl frag-
ment. In principle, given that this ligand can partition itself
into three potentially bidentate compartments, we might expect
a trinuclear double helicate with all three bidentate sites
occupied. We could not however isolate such a complex even
using an excess of the metal ion in the complexation reaction.
Such a structure appears to be disfavoured, possibly because of
the electrostatic barrier to having three dipositive metal ions
so close together; the Cu ؒ ؒ ؒ Cu separation in this dinuclear
helicate is 4.746 Å, and insertion of an additional metal ion
between them would result in unrealistically short metal–metal
separations. In addition, the helical ligand array is facilitated by
a substantial twist between the two halves of each ligand such
that the central bipyridyl unit of each is not coplanar. The
dihedral angle between the pyridyl rings containing N(251) and
N(252) is 36.6Њ, and the dihedral angle in the other bipyridyl
fragment is 48.5Њ. Such a substantial distortion from planarity
of the central bipyridyl fragments clearly precludes chelation to
a metal ion.
4
4+
Fig. 10 Alternative view of the complex cation [Cu (L ) ] ,
2
2
emphasising the four-coordinate cavity at the centre of the helicate.
about the metal ions, far from being pseudo-tetrahedral (as for
the previous complex with L ), is more like that of an octa-
3
hedron with a pair of cis coordination sites vacant, or a trigonal
bipyramid with one equatorial site vacant. The two thiazolyl
donors are almost perfectly trans to one another, with N–Cu–N
angles involving these donors of 173.9 and 173.4Њ at Cu(1) and
Cu(2) respectively. The irregular four-coordinate geometry and
the range of Cu–N bond distances (1.92 to 2.14 Å) could, as
before, be consistent with Cu() and well as Cu(), but the +2
oxidation state of the metal ions was confirmed by the presence
of characteristic d–d transitions at 740 and 1230 nm in the
3
Ϫ1
Ϫ1
electronic spectrum in MeNO (ε ca. 200 dm mol cm in
2
20
each case). This is in exact agreement with the expectation of
two distinct d–d transitions for Cu() chromophores with a cis-
with the large separation between the tran-
sitions reflecting the very high degree of rhombic distortion of
the cis-CuN X chromophore, i.e. X = nothing in this case! This
20,21
Again, the metal ions are in distorted four-coordinate geom-
etries with the values of θ [the angle between the two Cu(NN)
planes at each metal site] being 60.3Њ for Cu(1) and 59.7Њ for
Cu(2). This does not tell the whole story because the geometry
N X geometry,
4
2
4
2
strongly suggests that the solid-state structure is retained in
J. Chem. Soc., Dalton Trans., 2001, 550–559 555

View Article Online
nitromethane solution. Again, EPR analysis in MeNO solu-
NH), 10.24 (1H, s, NH), 8.70 (1H, d, py), 8.31 (1H, d, py), 8.15
(1H, t, py), 7.68 (1H, t, py). Found: C, 52.0; H, 4.4; N, 20.0%;
C H N S requires C, 52.1; H, 4.4; N, 20.3%.
2
tion allowed confirmation of the oxidation state as Cu() with a
broad, relatively featureless signal at g = 2.12, both at room
temperature and at 77 K. The appearance of the spectra as
broad and poorly-resolved may again be ascribed to Cu ؒ ؒ ؒ Cu
exchange coupling.
6
6
2
Preparation of pyridine-2,6-di(thioamide)
3
4+
This was prepared in exactly the same way as described for
An interesting feature of the structures of both [Cu (L ) ]
2
2
4
4+
pyridine-2-thioamide, by bubbling H
S for 1 h through a solu-
2
and [Cu (L ) ] is that the non-coordinated fragments in the
2
2
tion of 2,6-dicyanopyridine (3.0 g, 23.0 mmol) in a mixture of
middle of each ligand (a pyridyl residue in the former case, and
3
3
Et N (1 cm ) and ethanol (20 cm ). Filtration of the precipitate
3
a bipyridyl residue in the latter) define a central cavity between
3
4+
gave pure pyridine-2,6-di(thioamide) as a yellow solid. Yield:
the two metal ions. For [Cu (L ) ] , with a non-bonded
2
2
+
1
3
.44 g, 75%. EI-MS: m/z 197 (50%, M ). H NMR [300 MHz,
N ؒ ؒ ؒ N separation of 4.36 Å, there is a two-coordinate cavity
Fig. 8) which (steric hindrance apart) could be suitable for
binding a guest such as a small molecule with two hydrogen-
(
CD ) SO]: δ 10.50 (2H, s, NH), 10.26 (2H, s, NH), 8.75 (2H, d,
3
2
(
py), 8.13 (1H, t, py). Found: C, 42.4; H, 3.4; N, 21.0%;
C H N S requires C, 42.6; H, 3.6; N, 21.3%.
7 7 3 2
4
4+
bond donor sites. In [Cu (L ) ] the cavity is four-coordinate
2
2
from the two twisted bipyridyl units (Fig. 10), with N ؒ ؒ ؒ N
separations between the two bipyridyl fragments across the
cavity lying between 3.66 and 4.13 Å. Although binding of an
additional metal ion here is likely to be difficult (if not impos-
sible) for the reasons mentioned earlier, the shape and size of
the cavity could again be suitable for small-molecule binding via
hydrogen-bonding with the N atoms acting as the hydrogen-
bond acceptors. We note that binding of additional guest
species within a helical array has been demonstrated by the
1
4
Preparation of ligands L –L
1
L . To a solution of pyridine-2-thioamide (0.30 g, 2.17 mmol)
in methanol (15 cm ) a solution of 1,4-dibromobutane-2,3-
dione (0.26 g, 1.06 mmol) in methanol (15 cm ) was added and
the solution refluxed for 1 h. After this time the resulting yellow
precipitate was filtered, washed with ethanol (5 cm ) and Et O
(5 cm ) and dried in vacuo to give L ؒ2HBr. Yield: 0.41 g, 80%.
Found: C, 39.8; H, 2.0; N, 10.9%; C H N S Br requires C,
3
3
3
2
3
1
16
12
4
2
2
22
groups of Albrecht and Raymond, and similar studies with
39.7; H, 2.5; N, 11.6%.
3
4+
4
4+
1
[
Cu (L ) ] and [Cu (L ) ] are in progress.
The free base ligand L was prepared from the hydrobromide
2
2
2
2
1
Although the irregular four-coordinate geometries of the
salt as follows. L ؒ2HBr (0.20 g, 0.41 mmol) was suspended in
ammonia (0.88 S.G., 50 cm ) and left to stand for 12 h. During
3
4
3
metal centres in [Cu (L ) ][ClO ] and [Cu (L ) ][ClO ] suggest
2
2
4 4
2
2
4 4
that facile interconversion between Cu() and Cu() might be
possible with minimal rearrangement, cyclic voltammetric
studies (MeNO solvent, Bu NPF base electrolyte, Pt working
electrode) revealed no reversible electrochemical behaviour,
with only irreversible processes at high positive and negative
potentials.
this time the suspension changed colour from yellow to pink.
3
3
Filtration and washing with methanol (2 cm ) and Et O (2 cm )
2
1
gave L as a pale pink solid. Yield: 0.13 g, 100%. EI-MS:
m/z 322 (75%, M ). H NMR [300 MHz, (CD ) SO]: δ 8.68 (2H,
2
4
6
+
1
3 2
d, pyridyl), 8.26 (2H, d, py), 8.24 (2H, s, th), 8.23 (2H, t, py),
7.55 (2H, t, py) (py denotes the pyridyl group; th denotes the
thiazolyl group). Found: C, 59.5; H, 2.8; N, 16.9%; C H N S
4 2
16
10
1
requires C, 59.6; H, 3.1; N, 17.4%. L can be recrystallised
from MeCN to give colourless plates, but the ligand was gener-
ally sufficiently pure to use directly for the complexation
reactions.
Conclusions
1
4
The ligands L –L are versatile new ligands for the preparation
of double and triple helicate complexes with first-row
transition-metals. They are exceptionally easy to prepare, in
marked contrast to the linear polypyridines that are their
most obvious analogues. Their partitioning into bidentate or
terdentate binding domains is dependent on the position of the
thiazolyl rings in the ligand backbone.
2
L . To a solution of 1,10-phenanthroline-2-thioamide (0.49 g,
3
2.05 mmol) in methanol (25 cm ) a solution of 1,4-dibromo-
3
butane-2,3-dione (0.25 g, 1.0 mmol) in methanol (5 cm ) was
added and the resulting solution heated at reflux for 2 h. During
this time the colour changed from brown to green, and a green
3
solid separated. Filtration and washing with methanol (2 cm )
Experimental
3
2
and Et O (2 cm ) gave L ؒ2HBr as a green solid. Found: C, 52.6;
2
H, 2.4; N, 12.7%; C H N S Br requires C, 52.5; H, 2.6; N,
General details
30 18
6
2
2
1
1
2.2%. H NMR [300 MHz, (CD ) SO]: δ 9.38 (2H, d, phen),
3 2
The following instrumentation was used for routine spectro-
scopic measurements: NMR spectra, a JEOL Lambda 300
MHz spectrometer; mass spectra, a VG-Autospec instrument
9
.20 (2H, d, phen), 8.89 (2H, d, phen), 8.86 (2H, d, phen), 8.55
(
2H, s, th), 8.30 (6H, m, phen).
2
The free base ligand L was prepared from the hydrobromide
(
electron impact) or a VG-Quattro mass spectrometer (electro-
1
salt exactly as above for L in quantitative yield. Analytical
samples were recrystallised from hot dmso, but the ligand was
generally sufficiently pure to use directly for the complexation
spray ionisation); electronic spectra, a Perkin-Elmer Lambda 2
spectrometer. EPR spectra were recorded at X-band on a
Bruker ESP-3000E spectrometer.
+
reactions. EI-MS: m/z 524 (80%, M ). Found: C, 60.8; H, 3.6;
The following compounds were prepared by literature
N, 12.8%; C H N S ؒ2(Me SO) requires C, 60.0; H, 4.1; N,
1
3
30 16
6
2
2
methods: 1,4-dibromobutane-2,3-dione, 1,10-phenanthroline-
1
1
2.3%. A H NMR spectrum could not be obtained due to
1
4
13
2
2
-thioamide, 2-(α-bromoacetyl)pyridinium hydrobromide,
12
the poor solubility of the compound in common organic
solvents.
,2Ј-bipyridine-6,6Ј-di(thioamide). Starting materials were
purchased from the usual commerical sources (Aldrich,
Avocado, Lancaster) and used as received.
3
L . To a solution of pyridine-2,6-di(thioamide) (0.30 g, 1.5
3
mmol) in methanol (15 cm ) a solution of 2-(α-bromoacetyl)-
Preparation of pyridine-2-thioamide
pyridinium hydrobromide (1.12 g, 4.0 mmol) in methanol
3
2
-Cyanopyridine (10.0 g, 96.0 mmol) was dissolved in a mixture
(15 cm ) was added and the solution refluxed for 4 h. After this
3
3
of Et N (2 cm ) and ethanol (30 cm ). H S was slowly bubbled
time the resulting yellow precipitate was filtered, washed with
3
2
3
3
through the solution for 1 h, during which time a yellow precipi-
tate was formed. Collection by filtration gave pure pyridine-2-
thioamide as a yellow solid. Yield: 6.63 g, 50%. EI-MS: m/z 138
ethanol (5 cm ) and Et O (5 cm ) and dried in vacuo to give
2
3
L ؒ2HBr. The resulting hydrobromide salt was suspended in
ammonia (0.88 S.G., 50 cm ) and left to stand for 12 h. Fil-
tration and washing with methanol (2 cm ) and Et O (2 cm )
3
+
1
3
3
(
75%, M ). H NMR [300 MHz, (CD ) SO]: δ 10.51 (1H, s,
3
2
2
5
56
J. Chem. Soc., Dalton Trans., 2001, 550–559

View Article Online
3
1
gave L as a pale yellow solid. Yield: 0.42 g, 70%. EI-MS: m/z
0.010 g, 67%. H NMR (300 MHz, CD NO ): δ 9.35 (d, 4H,
3 2
+
1
3
99 (70%, M ). H NMR [300 MHz, (CD ) SO]: δ 8.71 (2H, m,
py), 8.50 (2H, s, th), 8.47 (4H, m, py), 8.28 (3H, m, py), 7.68
2H, m, py). Found: C, 62.7; H, 3.2; N, 17.2%; C H N S
requires C, 63.1; H, 3.3; N, 17.5%.
phen, J = 8.5), 8.90 (d, 4H, phen, J = 8.5), 8.53 (dd, 4H, phen,
J = 8.3, 1.4), 8.39 (d, 4H, phen, J = 9.1), 8.23 (d, 4H, phen,
J = 9.1), 7.68 (dd, 4H, phen, J = 4.8, 1.4), 7.50 (dd, 4H,
phen, J = 8.3, 4.8 Hz), 7.20 (s, 4H, th). ES-MS: m/z 1476
3
2
(
21 13 5 2
2
+
2
2+
[
Zn (L ) (ClO ) ] , 687 [Zn (L ) (ClO ) ] . Found: C, 45.6; H,
2 2 4 3 2 2 4 2
4
L . To a suspension of 2,2Ј-bipyridine-6,6Ј-di(thioamide)
0.20 g, 0.73 mmol) in methanol (15 cm ) a solution of 2-(α-
bromoacetyl)pyridinium hydrobromide (0.61 g, 2.19 mmol) in
methanol (15 cm ) was added and the solution refluxed for 4 h.
After this time the resulting yellow precipitate was filtered,
washed with ethanol (5 cm ) and Et O (5 cm ) and dried in
vacuo to give L ؒ2HBr. This hydrobromide salt was suspended
in ammonia (0.88 S.G., 50 cm ) and left to stand for 12 h.
2.0; N, 10.7%; C H N S Zn Cl O requires C, 45.7; H, 2.0;
60 32 12 4 2 4 16
3
(
N, 10.6%.
3
3
3
[
Cu (L ) ](ClO ) . To a suspension of L (0.010 g, 0.025
mmol) in nitromethane (2 cm ) Cu(ClO ) ؒ6H O (0.009 g, 0.02
mmol) was added and the solution stirred until dissolution was
complete. Filtration followed by slow vapour diffusion of ethyl
2
2
4 4
3
4
2
2
3
3
2
4
3
3
acetate into the solution gave [Cu (L ) ](ClO ) as large green
2
2
4 4
3
3
Filtration and washing with methanol (2 cm ) and Et O (2 cm )
3
2
crystals. Yield: 0.010 g, 61%. ES-MS: m/z 1224 [Cu (L ) -
2 2
+ 3 2+
4
gave L as a pale yellow solid. Yield: 0.28 g, 82%. EI-MS:
(
ClO ) ] , 562 [Cu (L ) (ClO ) ] . Found: C, 37.5; H, 2.1; N,
4 3 2 2 4 2
+
1
m/z 476 (50%, M ). H NMR [300 MHz, (CD ) SO]: δ 8.72 (2H,
3
2
10.0%; C H N S Cu Cl O requires C, 38.1; H, 2.0; N,
42 26 10 4 2 4 16
m, py), 8.61 (2H, d, py), 8.58 (2H, s, th), 8.40 (2H, d, py), 8.35
2H, d, py), 8.28 (2H, t, py), 8.10 (2H, m, py), 7.54 (2H, m, py).
Found: C, 66.0; H, 3.2; N, 17.1%; C H N S requires C, 65.5;
H, 3.4; N, 17.6%. A similar synthesis of L has already been
published.
1
0.6%.
Cu (L ) ](ClO ) . To a suspension of L (0.010 g, 0.021
mmol) in nitromethane (2 cm ) Cu(ClO ) ؒ6H O (0.007 g, 0.02
mmol) was added and the solution stirred until dissolution was
(
4
4
26
16
6 2
4
[
2
2
4 4
3
4
2
2
12
complete. Filtration followed by slow vapour diffusion of ethyl
Preparation of metal complexes
4
acetate into the solution gave [Cu (L ) ](ClO ) as large green
2
2
4 4
4
CAUTION: perchlorate salts are potentially explosive and
should be treated with due care. Those complexes described
below which were isolated as perchlorates were only prepared
in small amounts (10–20 mg) and we had no problems with
them.
crystals. Yield: 0.006 g, 41%. ES-MS: m/z 1378 [Cu
2
(L )
] . Found: C, 42.0; H, 2.0; N,
16 requires C, 42.2; H, 2.2; N,
-
2
+
4
2+
(ClO
)
] , 639 [Cu
(L )
Cu
(ClO
Cl
)
4
3
2
2
4 2
10.9%; C52
H
32
N
S
O
12
4
2
4
11.4%.
X-Ray crystallography
1
1
[
Cu (L ) ](PF ) . To a suspension of L (0.010 g, 0.03 mmol)
2
3
6
4
3
Diffraction intensity data were collected on a Siemens SMART-
CCD diffractometer. The software used was SHELXS-97 for
23
in acetone (2 cm ), Cu(PF ) ؒ6H O (0.009 g, 0.02 mmol) was
added and the suspension stirred until dissolution was com-
plete. Filtration followed by slow vapour diffusion of ethyl
acetate into the solution gave [Cu (L ) ](PF ) as large green
6
2
2
23
structure solution; SHELXL-97 for structure refinement;
2
4
1
and SADABS for the absorption correction. Details of
the crystal parameters, data collection and refinement are
collected in Table 1, and selected metric parameters are in
Tables 2–5.
CCDC reference number 186/2325.
See http://www.rsc.org/suppdata/dt/b0/b007922g/ for crystal-
lographic files in .cif format.
The structural determinations of the metal complexes tended
to be complicated by a combination of extensive solvation,
which resulted in poor crystallinity and weak data, and disorder
in the counter-ions and solvent molecules which could not
always be resolved. For [Zn (L ) ][ClO ] ؒ9MeCN the data were
very weak and it was only possible to refine the structure with
isotropic thermal parameters throughout; the esd’s on the
structural parameters for this complex are high and accordingly
the structure should be regarded only as confirming the gross
helical architecture of the complex. In each member of the
2
3
6 4
1
crystals. Yield: 0.010 g, 59%. ES-MS: m/z 1401 [Cu (L ) -
2
3
+
(
PF ) (HO)] . Found: C, 33.7; H, 2.0; N, 10.0%; C H N -
6
2
4
8
3
0
1
2
S Cu P F requires C, 33.9; H, 1.9; N, 10.5%.
6
2
4
24
1
1
[
Zn (L ) ](ClO ) . To a suspension of L (0.010 g, 0.03 mmol)
2 3 4 4
3
in nitromethane (2 cm ) Zn(ClO ) ؒ6H O (0.008 g, 0.02 mmol)
4
2
2
was added and the solution stirred until dissolution was com-
plete. Filtration followed by slow vapour diffusion of ethyl
acetate into the solution gave [Zn (L ) ](ClO ) as large colour-
less crystals. Yield: 0.007 g, 50%. H NMR (300 MHz,
1
2
3
4 4
1
2
CD NO ): δ 8.27 (12H, m, py), 7.97 (dt, 6H, py, J = 5.1, 1.1 Hz),
2
2
4 4
3
2
7
(
.59 (6H, m, py), 7.52 (6H, s, th). ES-MS: m/z 1396 [Zn -
2
1 + 1 2+
L ) (ClO ) ] , 648 [Zn (L ) (ClO ) ] . Found: C, 37.7; H, 2.0;
3 4 3 2 3 4 2
N, 10.6%; C H N S Zn Cl O requires C, 38.5; H, 2.0; N,
48
30 12
6
2
4
16
1
1.2%.
1
1
1
[
Co (L ) ](ClO ) . This was prepared (as orange crystals)
isostructural series [Cu
2
1
(L )
3
][PF
][ClO
]
6
4
ؒ4Me
ؒ4MeNO
2
2
CO, [Zn
2 3 4 4
(L ) ][ClO ] ؒ
2
3
4 4
1
from L and Co(ClO ) ؒ6H O in exactly the same way as for the
4MeNO
2
and [Zn (L )
2
3
4
]
4
one of the two
4
2
2
Zn() analogue above. Yield: 0.01 g, 70%. ES-MS: m/z 1383
independent solvent molecules is well defined but the other has
a highly irregular geometry with some residual electron-density
peaks nearby. Attempts to force the geometry to be more
regular using restraints were not successful, and attempts to
model the disorder more accurately by introducing a greater
number of parameters into the refinement led to the refinement
1
+
1
2+
[
Co (L ) (ClO ) ] , 642 [Co (L ) (ClO ) ] . Found: C, 37.9; H,
2 3 4 3 2 3 4 2
2
.0; N, 10.9%; C H N S Co Cl O requires C, 38.9; H, 2.0;
48 30 12 6 2 4 16
N, 11.3%.
2
2
[
Cu (L ) ](ClO ) . To a suspension of L (0.010 g, 0.019
2
2
4 4
3
mmol) in nitromethane (2 cm ) Cu(ClO ) ؒ6H O (0.007 g, 0.019
becoming unstable. Similar problems were encountered with
4
2
2
3
mmol) was added and the solution stirred until dissolution was
one of the solvent molecules of [Cu
2
(L )
][ClO
2
4
]
4
ؒ4MeNO
.
2
complete. Filtration followed by slow vapour diffusion of ethyl
A general feature of these structures is accordingly (i) high
thermal parameters for some of the solvent/anion atoms, and
(ii) residual electron-density peaks of up to 2 e Å associated
2
acetate into the solution gave [Cu (L ) ](ClO ) as green crys-
2
2
4 4
2
+
Ϫ3
tals. Yield: 0.007 g, 51%. ES-MS: m/z 1473 [Cu (L ) (ClO ) ] ,
86 [Cu (L ) (ClO ) ] . Found: C, 46.4; H, 2.1; N, 10.2%;
2
2
4 3
2
2+
6
with the disordered solvents/anions. With this in mind the
2
2
4 2
C H N S Cu Cl O requires C, 45.8; H, 2.0; N, 10.7%.
quality of the refinements is reasonable and the R values we
1
6
0
32 12
4
2
4
16
obtained (Table 1) are entirely typical of large, highly charged,
and highly solvated molecules of this general type. In all cases
the complex cations are clearly defined and well resolved with
no disorder problems.
2
2
[
Zn (L ) ](ClO ) . This was prepared from L (0.010 g,
2
2
4 4
0
.019 mmol) and Zn(ClO ) ؒ6H O (0.007 g, 0.019 mmol) in
exactly the same way as for the Cu() analogue above. Yield:
4 2 2
J. Chem. Soc., Dalton Trans., 2001, 550–559
557

View Article Online
2
2
Table 3 Selected bond lengths (Å) and angles (Њ) for [Cu (L ) ][ClO ] ؒ8MeCNؒH O and [Zn (L ) ][ClO ] ؒ9MeCN. Parameters which are equivalent
2
2
4
4
2
2
2
4 4
between the two structures are listed in the same row of the table
Cu(1)–N(121)
Cu(1)–N(144)
Cu(1)–N(124)
Cu(1)–N(141)
Cu(1)–N(111)
Cu(1)–N(101)
Cu(2)–N(244)
Cu(2)–N(221)
Cu(2)–N(241)
Cu(2)–N(224)
Cu(2)–N(201)
Cu(2)–N(211)
1.972(11)
1.987(11)
2.111(12)
2.138(13)
2.226(12)
2.311(13)
1.965(12)
1.968(12)
2.129(14)
2.148(11)
2.258(12)
2.299(13)
Zn(1)–N(124)
Zn(1)–N(141)
Zn(1)–N(121)
Zn(1)–N(144)
Zn(1)–N(101)
Zn(1)–N(111)
Zn(2)–N(221)
Zn(2)–N(244)
Zn(2)–N(224)
Zn(2)–N(241)
Zn(2)–N(201)
Zn(2)–N(211)
2.043(18)
2.103(19)
2.182(18)
2.185(17)
2.236(19)
2.215(19)
2.056(19)
2.043(19)
2.199(18)
2.204(17)
2.184(17)
2.249(17)
N(121)–Cu(1)–N(144)
N(121)–Cu(1)–N(124)
N(144)–Cu(1)–N(124)
N(121)–Cu(1)–N(141)
N(144)–Cu(1)–N(141)
N(124)–Cu(1)–N(141)
N(121)–Cu(1)–N(111)
N(144)–Cu(1)–N(111)
N(124)–Cu(1)–N(111)
N(141)–Cu(1)–N(111)
N(121)–Cu(1)–N(101)
N(144)–Cu(1)–N(101)
N(124)–Cu(1)–N(101)
N(141)–Cu(1)–N(101)
N(111)–Cu(1)–N(101)
N(244)–Cu(2)–N(221)
N(244)–Cu(2)–N(241)
N(221)–Cu(2)–N(241)
N(244)–Cu(2)–N(224)
N(221)–Cu(2)–N(224)
N(241)–Cu(2)–N(224)
N(244)–Cu(2)–N(201)
N(221)–Cu(2)–N(201)
N(241)–Cu(2)–N(201)
N(224)–Cu(2)–N(201)
N(244)–Cu(2)–N(211)
N(221)–Cu(2)–N(211)
N(241)–Cu(2)–N(211)
N(224)–Cu(2)–N(211)
N(201)–Cu(2)–N(211)
173.9(5)
79.3(5)
95.6(5)
98.7(5)
79.2(5)
102.1(5)
76.3(5)
109.3(5)
154.1(4)
90.0(4)
108.7(5)
74.3(5)
91.1(5)
151.4(4)
88.8(4)
173.6(5)
79.5(5)
98.2(5)
96.3(5)
78.4(5)
105.3(5)
110.7(5)
75.2(5)
88.8(5)
151.6(5)
74.7(5)
108.6(5)
151.6(5)
89.3(4)
89.3(4)
N(124)–Zn(1)–N(141)
N(124)–Zn(1)–N(121)
N(141)–Zn(1)–N(121)
N(124)–Zn(1)–N(144)
N(141)–Zn(1)–N(144)
N(121)–Zn(1)–N(144)
N(124)–Zn(1)–N(101)
N(141)–Zn(1)–N(101)
N(121)–Zn(1)–N(101)
N(144)–Zn(1)–N(101)
N(124)–Zn(1)–N(111)
N(141)–Zn(1)–N(111)
N(121)–Zn(1)–N(111)
N(144)–Zn(1)–N(111)
N(111)–Zn(1)–N(101)
N(244)–Zn(2)–N(221)
N(221)–Zn(2)–N(224)
N(244)–Zn(2)–N(224)
N(221)–Zn(2)–N(241)
N(244)–Zn(2)–N(241)
N(224)–Zn(2)–N(241)
N(221)–Zn(2)–N(201)
N(244)–Zn(2)–N(201)
N(201)–Zn(2)–N(224)
N(201)–Zn(2)–N(241)
N(221)–Zn(2)–N(211)
N(244)–Zn(2)–N(211)
N(224)–Zn(2)–N(211)
N(241)–Zn(2)–N(211)
N(201)–Zn(2)–N(211)
170.1(7)
74.6(7)
97.8(7)
98.3(7)
76.6(7)
100.9(6)
74.7(7)
113.6(7)
148.1(7)
91.9(7)
112.5(7)
73.4(7)
90.5(7)
149.1(7)
93.2(7)
169.0(7)
76.1(7)
96.8(7)
95.9(7)
77.0(7)
101.1(6)
114.8(7)
73.3(7)
91.7(7)
148.8(7)
73.6(7)
114.2(7)
148.9(7)
88.9(6)
94.6(6)
3
Table 4 Selected bond lengths (Å) and angles (Њ) for [Cu (L ) ][ClO ] ؒ4MeNO
2
2
4
4
2
Cu(1)–N(121)
Cu(1)–N(221)
Cu(1)–N(211)
Cu(1)–N(111)
1.956(5)
1.969(5)
2.007(5)
2.014(5)
Cu(2)–N(251)
Cu(2)–N(151)
Cu(2)–N(241)
Cu(2)–N(141)
1.971(5)
1.983(5)
2.016(5)
2.071(5)
N(121)–Cu(1)–N(221)
N(121)–Cu(1)–N(211)
N(221)–Cu(1)–N(211)
N(121)–Cu(1)–N(111)
N(221)–Cu(1)–N(111)
N(211)–Cu(1)–N(111)
159.6(2)
104.0(2)
81.9(2)
81.6(2)
106.3(2)
141.2(2)
N(251)–Cu(2)–N(151)
N(251)–Cu(2)–N(241)
N(151)–Cu(2)–N(241)
N(251)–Cu(2)–N(141)
N(151)–Cu(2)–N(141)
N(241)–Cu(2)–N(141)
161.7(2)
81.5(2)
103.8(2)
107.0(2)
81.1(2)
137.5(2)
4
Table 5 Selected bond lengths (Å) and angles (Њ) for [Cu (L ) ][ClO ] ؒ2MeNO
2
2
4
4
2
Cu(1)–N(111)
Cu(1)–N(101)
Cu(1)–N(121)
Cu(1)–N(131)
1.923(4)
1.928(4)
2.097(3)
2.134(4)
Cu(2)–N(211)
Cu(2)–N(201)
Cu(2)–N(221)
Cu(2)–N(231)
1.925(4)
1.930(4)
2.103(4)
2.136(4)
N(111)–Cu(1)–N(101)
N(111)–Cu(1)–N(121)
N(101)–Cu(1)–N(121)
N(111)–Cu(1)–N(131)
N(101)–Cu(1)–N(131)
N(121)–Cu(1)–N(131)
173.87(16)
79.81(14)
101.47(15)
104.86(15)
79.62(15)
122.29(14)
N(211)–Cu(2)–N(201)
N(211)–Cu(2)–N(221)
N(201)–Cu(2)–N(221)
N(211)–Cu(2)–N(231)
N(201)–Cu(2)–N(231)
N(221)–Cu(2)–N(231)
173.36(15)
79.24(15)
101.55(15)
106.15(15)
79.05(15)
123.09(14)
Leverhulme foundation for financial support. We would also
like to thank Dr John Maher (University of Bristol) for record-
ing the EPR spectra.
Acknowledgements
We thank the University of Huddersfield, the EPSRC, and the
5
58 J. Chem. Soc., Dalton Trans., 2001, 550–559

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1
3 R. Menasse, G. Klien and H. Erlenmeyer, Helv. Chim. Acta., 1955,
289.
References
1
1
C. Piguet, G. Bernardinelli and G. Hopfgartner, Chem. Rev., 1997,
7, 2005; E. C. Constable, in Polynuclear Transition Metal Helicates,
14 H. A. Goodwin, F. E. Smith, E. König and G. Ritter, Aust. J. Chem.,
1973, 26, 521.
9
vol. 9, Comprehensive Supramolecular Chemistry, editor: J.-P.
Sauvage, Elsevier, Oxford, 1996, pp. 213–252.
M. Albrecht, Chem. Soc. Rev., 1998, 27, 281; M. Albrecht, O. Blau
and H. Röttele, New J. Chem., 2000, 24, 619.
M. Elhabiri, R. Scopelliti, J.-C. G. Bunzli and C. Piguet, J. Am.
Chem. Soc., 1999, 121, 10747; S. Rigault, C. Piguet and J.-C. G.
Bünzli, J. Chem. Soc., Dalton Trans., 2000, 2045; C. Piguet, J. Incl.
Phenom. Macrocycl. Chem., 1999, 34, 361.
R. Stiller and J.-M. Lehn, Eur. J. Inorg. Chem., 1998, 977; B.
Hasenknopf, J.-M. Lehn, N. Boumediene, E. Leize and A. van
Dorsselaer, Angew. Chem., Int. Ed., 1998, 37, 3265.
15 E. C. Constable, S. M. Elder, J. V. Walker, P. D. Wood and D. A.
Tocher, J. Chem. Soc., Chem. Commun., 1992, 229; and refs. therein;
K. T. Potts, K. A. G. Rayford and M. Keshavarz-K, J. Am. Chem.
Soc., 1993, 115, 2793.
16 R. E. Rosenfeld, Jr., R. Parthasarathy and J. D. Dunitz, J. Am.
Chem. Soc., 1977, 99, 4860; T. N. G. Row and R. Parthasarathy,
J. Am. Chem. Soc., 1981, 103, 477.
17 M. A. Leech, N. Solanki, M. A. Halcrow, J. A. K. Howard and
S. Dahaoui, Chem. Commun., 1999, 2245; J.-V. Folgado, W. Henke,
R. Allmann, H. Stratemeier, D. Beltrán-Porter, T. Rojo and
D. Reinen, Inorg. Chem., 1990, 29, 2035.
18 E. C. Constable, Adv. Inorg. Chem. Radiochem., 1986, 30, 69;
B. Whittle, E. L. Horwood, L. H. Rees, S. R. Batten, J. C. Jeffery and
M. D. Ward, Polyhedron, 1998, 17, 373.
2
3
4
5
J. S. Fleming, E. Psillakis, S. M. Couchman, J. C. Jeffery, J. A.
McCleverty and M. D. Ward, J. Chem. Soc., Dalton Trans., 1998,
5
37; M. J. Hannon, S. Bunce, A. J. Clarke and N. W. Alcock, Angew.
Chem., Int. Ed., 1999, 38, 1277; N. K. Solanki, A. E. H. Wheatley,
S. Radojevic, M. McPartlin and M. A. Halcrow, J. Chem. Soc.,
Dalton Trans., 1999, 521; O. Mamula, A. von Zelewsky, T. Bark
and G. Bernardinelli, Angew. Chem., Int. Ed., 1999, 38, 2945;
R. Ziessel, A. Harriman, A. El-Ghayoury, L. Douce, E. Leize,
H. Nierengarten and A. van Dorsselaer, New J. Chem., 2000, 24,
19 D. A. Bardwell, A. M. W. Cargill Thompson, J. C. Jeffery, E. E. M.
Tilley and M. D. Ward, J. Chem. Soc., Dalton Trans., 1995, 835; P. J.
Burke, D. R. McMillin and W. R. Robinson, Inorg. Chem., 1980, 19,
1211; M. Geoffroy, M. Wermeille, C. O. Buchecker, J.-P. Sauvage and
G. Bérnardinelli, Inorg. Chim. Acta, 1990, 167, 157; M. Cesario,
C. O. Dietrich-Buchecker, T. Guilhem, C. Pascard and J.-P. Sauvage,
J. Chem. Soc., Chem. Commun., 1985, 244; K. Klemens, C. E. A.
Palmer, S. M. Rolland, P. E. Fanwick, D. R. McMillin and J.-P.
Sauvage, New J. Chem., 1990, 14, 129.
20 B. J. Hathaway, in Comprehensive Coordination Chemistry, editors:
G. Wilkinson, R. D. Gillard and J. A. McCleverty, Pergamon, 1987,
vol. 5, p. 533.
21 B. J. Hathaway and D. E. Billing, Coord. Chem. Rev., 1970, 5, 143;
W. Fitzgerald and B. J. Hathaway, J. Chem. Soc., Dalton Trans.,
1981, 567.
22 M. Albrecht, O. Blau and J. Zauner, Eur. J. Org. Chem., 1999, 3165;
M. Albrecht, M. Schneider and H. Röttele, Angew. Chem., Int. Ed.,
1999, 38, 557; M. Albrecht, O. Blau and R. Fröhlich, Chem. Eur. J.,
1999, 5, 48; M. Albrecht, O. Blau, E. Wegelius and K. Rissanen,
New J. Chem., 1999, 23, 667; J. Xu, T. N. Parac and K. N. Raymond,
Angew. Chem., Int. Ed., 1999, 38, 2878.
23 G. M. Sheldrick, SHELXS-97 and SHELXL-97, University of
Göttingen, Göttingen, 1997.
24 G. M. Sheldrick, SADABS, A program for absorption correction
with the Siemens SMART area-detector system, University of
Göttingen, Göttingen, 1996.
7
29.
6
7
E. C. Constable, Prog. Inorg. Chem., 1994, 42, 67.
K. T. Potts, Bull. Soc. Chim. Belg., 1990, 99, 741; K. T. Potts,
M. Keshavarz-K, F. S. Tham, H. D. Abruña and C. Arana, Inorg.
Chem., 1993, 32, 4436; K. T. Potts, M. P. Wentland, D. Ganguly,
G. D. Storrier, S. K. Cha, J. Cha and H. D. Abruña, Inorg. Chim.
Acta, 1999, 288, 189.
8
9
E. C. Constable, S. M. Elder, J. Healy and D. A. Tocher, J. Chem.
Soc., Dalton Trans., 1990, 1669; E. C. Constable, S. M. Elder,
J. Healy, M. D. Ward and D. A. Tocher, J. Am. Chem. Soc., 1990,
1
12, 4590.
E. C. Constable, S. M. Elder, M. J. Hannon, A. Martin, P. R.
Raithby and D. A. Tocher, J. Chem. Soc., Dalton Trans., 1996,
2
423.
1
1
1
0 E. C. Constable, M. D. Ward and D. A. Tocher, J. Chem. Soc.,
Dalton Trans., 1991, 1675.
1 C. R. Rice, S. Wörl, J. C. Jeffery, R. L. Paul and M. D. Ward, Chem.
Commun., 2000, 1529.
2 P. N. W. Baxter, J. A. Connor, W. B. Schweizer and J. D. Wallis,
J. Chem. Soc., Dalton Trans., 1992, 3015.
J. Chem. Soc., Dalton Trans., 2001, 550–559
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